Repair of retinal pigment epithelium and its relationship with capillary endothelium after krypton laser photocoagulation.

The regeneration of the retinal pigment epithelial (RPE) cells and their relationship with the vascular endothelium were studied during the healing of laser burns produced by krypton laser photocoagulation in rats. During the healing process the epithelial sheet was reformed by a morphologically heterogeneous population of RPE cells, some of which resembled macrophages. There seems to be a correlation between the specific phenotype of the regenerated RPE cell and the state of vitality of the adjacent endothelium. This was particularly evident in the scattered foci of choroidal subretinal neovascularization surrounded by RPE cells. One possible explanation for this apparent correlation is that the cytologic variations of the RPE cells reflect the multiple functions of a single cell which is expressed differently in different situations and in the course of interaction with other cells. This presumed ability of RPE cells may explain an intriguing aspect of cell-cell interaction, namely, the dual stimulatory and inhibitory effects of RPE cells on the vascular endothelium.